1. Field of the Invention
The present invention relates to an image synthesis suitable for high quality texture mapping in the field of three dimension computer graphics, particularly to a high-dimensional texture synthesis apparatus to synthesize a texture image of an arbitrary size according to conditions such as a viewpoint direction and a light source direction, and a high-dimensional texture synthesis method.
The present invention relates to an image synthesis suitable for high quality texture mapping in the field of three dimension computer graphics, particularly to a multi-dimensional texture synthesis apparatus to synthesize a texture image of an arbitrary size according to conditions such as a viewpoint direction and a light source direction, and a multi-dimensional texture synthesis method.
2. Description of the Related Art
The posture of a three-dimension object, that is, the shape of the three-dimensional object and the surface color and quality impression thereof vary based upon a direction (a viewpoint direction) watching the three-dimensional object and a direction (a light source direction) irradiating a light beam. In a field of three-dimensional computer graphics, the surface of three-dimensional object is divided into a number of two-dimensional plains called polygons, the drawing is executed every polygon to create a two-dimensional image to be used as a display image of three-dimensional object.
The posture of the three-dimensional object when the viewpoint direction and light source direction vary can be expressed by changing a direction of display polygon (three-dimensional posture) and the optical characteristic of the polygon (brightness) along with the viewpoint direction and light source direction. However, computation of a relation between a normal defining a direction (three-dimensional posture) of the polygon that is a drawing unit and a viewpoint direction or a light source direction needs a vector operation of floating point precision. This results in increasing a computing cost and complicating practical use in terms of hardware and software.
In late years, a scheme for synthesizing a texture image of an arbitrary size by small texture images is proposed (Li-Yi Wei, Marc Levoy, “Fast Texture Synthesis Using Tree-structured Vector Quantization”, Proceedings SIGGRAPH 2000, pp. 479–488, and Michael Ashikhmin, “Synthesizing Natural Textures”, 2001 ACM Symposium on Interactive 3D Graphics, pp. 217–226). This scans a texture image of an arbitrary size referring to an original small texture image and synthesizes a texture image near to the original image.
In addition, there is proposed a scheme for preparing a target texture image other than the referring small texture image and synthesizing an image having the design and pattern of the referring texture image and resembling the materials of the referring small texture image.
However, such a conventional texture image synthesis technology synthesizes merely a simple texture image, and cannot synthesize in a lump a number of texture images concerning multiple viewpoints and multiple light sources.
As described above, when the optical characteristic of the object surface varying according to a viewpoint direction and a light source direction is expressed in texture, a large number of texture images that differ in the viewpoint direction and light source direction are necessary, resulting in enormous computing quantity.